关于Mordell方程y^2=x^3＋k

设l,l1,l2,…,ls为任意整数,n为正整数,n1,n2,…,ns为任意非负整数．用初等数论方法证明了：如果k满足k=（4l＋2）^3-Пi=1^s（4li＋1）^2ni或k=（4l＋3）^3-2^2nПi=1^s（4li＋1）^2ni,则Mordell方程y^2=x^3＋k无整数解．     

Enabling Mg metal anodes rechargeable in conventional electrolytes by fast ionic transport interphase

Rechargeable magnesium batteries have received extensive attention as the Mg anodes possess twice the volumetric capacity of their lithium counterparts and are dendrite-free. However, Mg anodes suffer from surface passivation film in most glyme-based conventional electrolytes, leading to irreversible plating/stripping behavior of Mg. Here we report a facile and safe method to obtain a modified Mg metal anode with a Sn-based artificial layer via ion-exchange and alloying reactions. In the artificial coating layer, Mg₂Sn alloy composites offer a channel for fast ion transport and insulating MgCl₂/SnCl₂ bestows the necessary potential gradient to prevent deposition on the surface. Significant improved ion conductivity of the solid electrolyte interfaces and decreased overpotential of Mg symmetric cells in Mg(TFSI)₂/DME electrolyte are obtained. The coated Mg anodes can sustain a stable plating/stripping process over 4000 cycles at a high current density of 6 mA cm⁻². This finding provides an avenue to facilitate fast ion diffusion kinetics of Mg metal anodes in conventional electrolytes.     

Replication,pathogenicity, and transmission of SARS-CoV-2 in minks

Minks are raised in many countries and have transmitted severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans. However, the biologic properties of SARS-CoV-2 in minks are largely unknown. Here, we investigated and found that SARS-CoV-2 replicates efficiently in both the upper and lower respiratory tracts, and transmits efficiently in minks via respiratory droplets; pulmonary lesions caused by SARS-CoV-2 in minks are similar to those seen in humans with COVID-19. We further found that a spike protein-based subunit vaccine largely prevented SARS-CoV-2 replication and lung damage caused by SARS-CoV-2 infection in minks. Our study indicates that minks are a useful animal model for evaluating the efficacy of drugs or vaccines against COVID-19 and that vaccination is a potential strategy to prevent minks from transmitting SARS-CoV-2.     

新工科课程体系中的工程设计思维

工程思维和设计思维是新工科建设活动中的基本思维.通过对人才培养课程体系、专业知识结构体系、专业课程和跨学科课程等新工科建设活动中设计特征分析,提出在新工科课程体系建设中应重视工程思维和设计思维的融合,即"工程设计思维",体现新工科课程体系的创新性、系统性和实践性;在新工科课程教学活动中应重视对学习者工程设计思维的培养,...     

小粒子Mie散射理论及应用（Ⅰ）

本详细综述了近几年小粒子Mie散射的理论基础及其发展。     

论社会弱势群体的成因及其扶助措施

弱势群体问题关系着社会稳定的大局,已成为时下中国社会关注的热点问题。本文客观剖析了弱势群体产生的原因,提出了扶助社会弱势群体的具体措施。     

Static analysis of synchronism deployable antenna

INTRODUCTION Large antennas for space applications have some differences as compared to their counterparts de-signed and manufactured for ground usage. For a larger space antenna, the applied loads in space can be several orders of magnitude less than the gravity loading it is subjected to when being fabricated and assembled on the ground. Since the effect of gravity cannot be removed from any experimental verifica-tion performed on the ground, we must rely on the use of efficient and hig…     

汉英表量结构中隐喻的分类及认知解读

以＂合成空间理论＂为理论背景,研究汉英表量结构中隐喻的分类与认知解读问题。根据输入空间的不同,从认知角度将汉英表量结构中的隐喻分为两类：显性隐喻和隐性隐喻。显性隐喻是通过＂量词＂和＂名词＂两个输入空间之间的概念整合进行建构的,而隐性隐喻是通过量词所描述的＂原型名词＂和表量结构中的＂名词＂两个输入空间之间的概念整合进行建构的。     

山东省高校体育教师髌骨损伤及治疗方法的调查分析

运用文献资料法、问卷调查法和数理统计法,对山东省高校在职体育教师的髌骨损伤情况进行调查,结果显示：1）男女教师髌骨受损的发生率相比无显著差异（P〉0．05）;2）男女教师急性髌骨损伤在各年龄组间有显著差异,教龄短者更易于受损伤;3）教师各年龄组间慢性髌骨受损情况有非常显著性差异（P〈0．01）以教龄〉10年以上受损率最高,其受伤原因为冲撞、跳跃、扭伤,据此提出治疗康复方法。     

Shadow Play Drama Performed in China’s Xiaoyi

<正>Xiaoyi is a county located in the central part of north China’s Shanxi province. Over the sweep of history, many theatre forms were and developed in Xiaoyi, ...